Glycidyl dinitropropyl formal, poly(glycidyl dinitropropyl formal) and preparation method thereof

ABSTRACT

Disclosed are novel compounds that can be used as an energetic binder used for improving the performance and the properties of a high explosive, and a preparation method thereof. More specifically, provided are glycidyl dinitropropyl formal of chemical formula IV having a nitro group (—NO 2 ) as an energy group and having no hydrogen bonding to carbon to which the nitro group is binding, poly(glycidyl dinitropropyl formal) of chemical formula V polymerized using the glycidyl dinitropropyl formal as a monomer, and a preparation method thereof.

PRIORITY CLAIM

This application claims priority from Korean patent application no.27807/2003, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a synthesis of an energetic prepolymerused as a high-energy binder for an insensitive and high performanceexplosive.

2. Description of the Background Art

Currently, HTPB (Hydroxyl-Terminated Polybutadiene), a prepolymer for abinder for Plastic-Bonded Explosives (PBX's) is being widely used as abinder for polyurethane groups. This binder is included in PBX in theamount of about 15% to improve mechanical properties of PBX's. However,this binder is an inert material, and thereby causing reduction ofenergy of PBX's. Therefore, many efforts are made to develop ahigh-energy contained binder (an energetic binder) for increasing theenergy of PBX's.

As a result of such efforts, various energetic binders have beendeveloped such as PNG [poly(glycidyl nitrate)] as expressed as thefollowing chemical formula 1, PNMMO[poly(3-nitratomethyl-3-methyloxetane)], and the like. However, theabove prepolymers show poor thermal stabilities, since they containnitrate groups as an energy group, whereby the thermal decompositiononset temperature appears at about 180° C. Especially as shown inreaction scheme 1, the PGN is self-decomposed in a polyurethaneelastomer when the polyurethane elastomer is synthesized.

As shown in reaction scheme 1, when the polyurethane elastomer issynthesized by using PGN of chemical formula 1, hydrogen bonding tocarbon to which a nitrate group binds is chemically acidified thus toeasily cause a decomposition reaction as shown in reaction scheme 1,thereby causing a decomposition of the main chain of polyurethane.Nevertheless, since the PGN has been known as a material having the bestperformance among existing energetic prepolymers, many researches aremade in order to solve such problems. However, outstanding results havenot been obtained yet.

SUMMARY OF THE INVENTION

Therefore, in the present invention, in order to improve the thermalstability of the energetic binder, a nitro group is introduced insteadof the nitrate group. Further, in order to solve a self-decompositionproblem in the conventional polyurethane binder prepared by using PGN,the present invention provides a compound having no hydrogen bonding tocarbon to which the nitro group binds. The present invention introducesthe nitro group instead of the nitrate group, and thereby enables toprovide a prepolymer having an improved thermal stability compared withthat of the conventional energy binder. Moreover, the present inventionuses inexpensive initiating and intermediate materials and can achieve ahigh yield of the product, thus to be advantageous in the economicalaspect.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 shows an experimental result for the thermal stability ofpoly(glycidyl dinitropropyl formal) according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

The present invention provides novel compounds for use in an energeticbinder for improving the performance and properties of a high explosive.More particularly, the present invention provides glycidyl dinitropropylformal having a nitro group as an energy group, having no hydrogenbonding to carbon to which the nitro group binds, as expressed bychemical formula IV, poly(glycidyl dinitropropyl formal) polymerized byusing the glycidyl dinitropropyl formal as a monomer, as expressed bychemical formula V, and a preparation method thereof.

In the present invention, the novel compound, glycidyl dinitropropylformal of chemical formula IV, is used as a monomer for synthesizing thenovel compound, poly(glycidyl dinitropropyl formal) of chemical formulaV. Poly(glycidyl dinitropropyl formal) of chemical formula V is veryuseful as an energetic prepolymer due to an excellent thermal stabilityand a characteristic that it is not self-decomposed in synthesizing apolyurethane elastomer. The existing energetic prepolymer contains anitrate group having a low thermal stability as an energy group, andthereby has a low thermal stability. However, an energetic binderprepared by the compound of the present invention containing a nitrogroup as an energy group has an improved thermal stability compared withthat of the existing energetic prepolymer. Further, the presentinvention uses inexpensive initiating and intermediate materials and canachieve a high yield of the product, thus to be very economical.

A process for synthesizing glycidyl dinitropropyl formal of chemicalformula IV and poly(glycidyl dinitropropyl formal) of chemical formula Vis shown in the following reaction scheme 2.

Said reaction scheme will be explained in more detail as follows.

Firstly, 2,2-dinitripropanol (DNP-OH) of chemical formula I and allylalcohol of chemical formula II are reacted with boron trifluorideetherate to obtain allyl 2,2-dinitropropyl formal (ADNPF) of chemicalformula III (Reaction scheme 2-1).

Then, the obtained allyl 2,2-dinitropropyl formal (ADNPF) is reactedwith metha-chloroperbenzoic acid (m-CPBA) to obtain glycidyldinitropropyl formal of chemical formula IV (Reaction scheme 2-2).

The obtained glycidyl dinitropropyl formal is polymerized in a mixedsolution of boron trifluoride etherate and 1,4-butandiol (1,4-BD), toobtain poly(glycidyl dinitropropyl formal) of chemical formula V(Reaction scheme 2-3).

The obtained poly(glycidyl dinitropropyl formal) has an excellentthermal stability and does not include unstable hydrogen group thus notto cause a self-decomposition when preparing a polyurethane elastomer,thereby being very useful as a new energetic prepolymer that can be usedas an energetic binder for an insensitive and high performanceexplosive.

Hereinafter, the present invention will be explained in more detail withreference to preferred examples.

EXAMPLE 1 Synthesis of Allyl Dinitropropyl Formal (ADNPF)

15 g (0.1 mol) of 2,2-dinitropropanol (DNP-OH) of chemical formula I,3.3 g (0.11 mol) of formaldehyde and a desired amount (wherein theequivalent is controlled) of allyl alcohol of chemical formula II wereput in a 250 ml 3-necks round bottom flask equipped with a thermometerand a dropping funnel and 40 g of methylene chloride (MC) in whichmoisture has been removed was put therein. The temperature of thesolution was lowered to 5° C. or below, and 42.6 g (0.3 mol) of borontrifluoride etherate was slowly injected thereto with maintaining thetemperature of the reaction solution at 5° C. After injection, thesolution was strongly stirred with maintaining the temperature of thesolution at 5° C. or below for approximately 40 minutes, and then thereaction was completed.

After the reaction, 100 ml of distilled water was slowly added to thereaction mixture, stirred, and phase-separated in the separating funnel.An organic layer was washed with 5% caustic soda solution three times,with distilled water one time, with sodium chloride solution one time,and then with distilled water one time. Then, the resulting product wasdried with anhydrous magnesium sulfate and the solvent was removed, toobtain allyl dinitropropyl formal of chemical formula III.

NMR(CDCl₃, δ for TMS); 2.18(s, 3H), 4.0(d, 2H), 4.33(s, 2H), 4.71(s,2H), 5.2(m, 2H), 5.8(m, 1H)

Herein, a yield of the allyl dinitropropyl formal (AN/DNPF) becomesdifferent depending on the reaction condition, and a result depending ona composition ratio between alcohols was shown in the following table 1.In order to obtain allyl dinitropropyl formal of a high purity, afractional distillation was performed using a Thin Film Evaporator (TFE,a capacity: 1 L, Pope) with setting a temperature of an outer wall as100° C. TABLE 1 DNP-OH:allyl Crude Concentration of ADNPF Final yield ofalcohol yield of (Result of GC ADNPF (mol ratio) ADNPF (%) analysis, %)(%) 1:3 94.4 78.0 73.6 1:2 86.1 75.0 64.6 1:1 79.2 67.0 53.1

EXAMPLE 2 Synthesis of Glycidyl Dinitropropyl Formal (GDNPF)

33 g (0.15 mol) of allyl dinitropropyl formal and 400 g of chloroformwere put into a 1-neck round bottom flask of 1L equipped with athermometer and a reflux condenser. Then, 45 g (0.18mol) ofmeta-chloroperbenzoic acid (m-CPBA) was injected thereto throughapproximately 30 minutes. Since an exothermic reaction may occur whenm-CPBA is poured at one time, m-CPBA was slowly injected thereto. Afterinjecting all the m-CPBA, the temperature of the flask was slowly raisedto a reflux temperature of the solvent, and then the reaction solutionwas strongly stirred for about 3 hours. After three hours, the heatingwas stopped and a reaction was performed at the normal temperature for12 hours.

After completing the reaction, the reaction was lowered to 0° C. orbelow, and metha-chlorobenzoic acid (m-CBA) produced from the reactionand non-reacted m-CPBA were filtered as a solid crystal and extracted.Then, the solution was washed two times with 5% sodium sulfite, and wassufficiently washed with 5% sodium hydroxide until m-CBA is completelyremoved. The solution was washed one time with saturated sodium chloridesolution, dried with anhydrous magnesium sulfate, and filtrated. Then,the solvent was removed, volatile matters were completely removed by avacuum pump, and impurities were removed by using a thin film evaporatorat 90° C., to obtain 32.56 g of glycidyl dinitropropyl formal ofchemical formula IV (yield: 92%).

NMR(CDCl₃, δfor TMS); 2.17(s, 3H), 2.60(t, 1H), 2.78(t, 1H), 3.1(m,1H),3.8(m,1H), 4.3(s, 2H), 4.7(s, 2H)

Preferred Embodiment 3 Synthesis of Poly(glycidyl Dinitropropyl Formal)[p(GDNPF)]

0.18 g (2 mmol) of 1,4-butandiol was added to 28 g (1 mmol) of borontrifluoride etherate, then ether was completely removed by decompressionfor approximately 2 hours, and then 12 g of methylene chloride (MC) wasadded thereto. 11.5 g (50 mmol) of the glycidyl dinitropropyl formalobtained in example 2, which was dissolved in methylene chloride, wasinjected to the reaction solution for approximately three hours.

After injection, the resulting solution was additionally reacted for 30minutes to complete a polymerization reaction. Then, the solution waswashed with 50 ml of water and 30 ml of methylene chloride. Next, thesolution was washed three times with 50 ml of saturated sodium chloridesolution, and then dehydrated by anhydrous magnesium sulfate. Then, 20ml of ethanol was added to the obtained polymer and the reaction mixturewas stirred to wash out the non-reacted organic material. The pressurewas reduced at 1 mmHg/80° C. for 5 hours to completely remove volatilematters. A prepolymer poly(glycidyl dinitropropyl formal) of chemicalformula V having a numeric average molecular weight of 2,200, apolydispersity of 1.12, a hydroxyl group of 0.621 eq/kg, a glasstransition temperature of −23° C., and a thermal decompositioninitiating temperature of 200° C. or more was obtained with the yield ofabout 90%.

EXAMPLE 4 Thermal Decomposition Property of Poly(Glyicidyl DinitropropylFormal)

Dissociation energy of nitro group (—NO₂) according to a material towhich it binds was shown in the following table 2. As shown in the table2, the dissociation energy of X—NO₂ becomes greatly different accordingto the binding position of nitro group, and appears the greatest valuewhen the nitro group bonds to carbon. Accordingly, it can be predictedthat a compound in which a nitro group is bonding to carbon like in thepresent invention has a high thermal stability (Jimmie C. Oxley, JamesL. Smith, and ZunLiang Zhou, J. Phys. Chem, 99, 10383-10391,1995). TABLE2 Dissociation energy of X-NO₂ according to the binding material (X) XDissociation energy (kcal/mol) O 40 N 47 C 70

The thermal decomposition property of poly(glycidyl dinitropropylformal) prepared in example 3 was shown in FIG. 1. For the test ofthermal decomposition property, a loss weight of poly (glycidyldinitropropyl formal) by being decomposed was measured by raising thetemperature from normal temperature at the rate 10° C./min using the TGA(Mettler company) in the manner of being conventionally used in therelated art. As shown in FIG. 1, poly(glycidyl dinitropropyl formal)according to the present invention is thermally stable even at thetemperature of 200° C. or more.

The present invention relates to a novel compound that can be used as anenergetic binder for improving the performance and the property of ahigh explosive. The existing energetic binders have shown a low thermalstability due to containing a nitrate group having a low thermalstability as an energy group. However, the energetic binder preparedusing the compound of the present invention containing a nitro group asan energy group shows a improved thermal stability compared with theexisting energetic binders. Further, the compounds of the presentinvention are not self-decomposed, and thus, they are very useful as anenergetic prepolymer used as a energetic binder and a monomer thereof.Additionally, the present invention uses an inexpensive initiatingmaterial and intermediate material and achieves a high yield, therebybeing economical.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

1. Glycidyl dinitropropyl formal expressed as the following chemicalformula IV.


2. Poly(glycidyl dinitropropyl formal) expressed as the followingchemical formula V comprising the compound as a monomer.


3. Poly(glycidyl dinitropropyl formal) of claim 2, used as an energeticprepolymer that can be used as an energetic binder in a preparation of ahigh performance insensitive explosive.
 4. A preparation method ofPoly(glycidyl dinitropropyl formal) of claim 2 comprising the followingsteps of: as shown in the following reaction scheme 2-1, reacting2,2-dinitropropyl alcohol of chemical formula I with allyl alcohol ofchemical formula II to obtain allyl dinitropropyl formal of chemicalformula III;

as shown in the following reaction scheme 2-2, obtaining glycidyldinitropropyl formal expressed as the chemical formula IV from theobtained allyl dinitropropyl formal of chemical formula III; and

as shown in the following reaction scheme 2-3, polymerizing the obtainedglycidyl dinitropropyl formal to synthesize poly(glycidyl dinitropropylformal) expressed as chemical formula V.